Sex-Specific Effects of Nutritional Supplements for Infants Born Early or Small: An Individual Participant Data Meta-Analysis (ESSENCE IPD-MA) II: Growth

Neonatal nutritional supplements may improve early growth for infants born small, but effects on long-term growth are unclear and may differ by sex. We assessed the effects of early macronutrient supplements on later growth. We searched databases and clinical trials reg-isters from inception to April 2019. Participant-level data from randomised trials were included if the intention was to increase macronutrient intake to improve growth or development of infants born preterm or small-for-gestational-age. Co-primary outcomes were cognitive impairment and metabolic risk. Supplementation did not alter BMI in childhood (kg/m²: adjusted mean difference (aMD) −0.11[95% CI—0.47, 0.25], p = 0.54; 3 trials, n = 333). Supplementation increased length (cm: aMD 0.37[0.01, 0.72], p = 0.04; 18 trials, n = 2008) and bone mineral content (g: aMD 10.22[0.52, 19.92], p = 0.04; 6 trials, n = 313) in infancy, but not at older ages. There were no differences between supplemented and unsupplemented groups for other outcomes. In subgroup analysis, supplementation increased the height z-score in male toddlers (aMD 0.20[0.02, 0.37], p = 0.03; 10 trials, n = 595) but not in females, and no significant sex interaction was observed (p = 0.21). Macronutrient supplementation for infants born small may not alter BMI in childhood. Supplemen-tation increased growth in infancy, but these effects did not persist in later life. The effects did not differ between boys and girls.